Dermatology Flashcards
What is Steven’s Johnson syndrome
Severe form of erythema multiforme and a variant of toxic epidermal necrolysis
Name 6 drug causes Steven’s Johnson
- Sulphonamides (bactrim)
- NNRTI: efavirenz, nevirapine
- penicillin
- barbiturates (CNS depressant eg phenobarbital)
- salicylates
- carbamazepine, phenytoin
What is toxic epidermal necrolysis
Blistering > 30% of skin surface area
Erythema nodosum vs multiforme vs marginatum is infectiosum?
- Nodosum: painful subcutaneous nodules on shins. One of causes is IBD.
- multiforme: dusky, targetOid rash after infection / drug
- marginatum: rheumatic fever
- erythema infectiosum: parvovirus b 19 - slapped cheek
Erythema multiforme vs Steven’s Johnsons vs TEN? (5)
- < 10% TBSA vs 10 - 30 vs > 30%
- hands / forearms / oral vs 2 or more mucosal sites vs everywhere
- target lesions vs - vs peeling: positive Nikolsky’s sign
- vs more common in children vs elderly
- vs URI prodrome vs abrupt onset
Define macule
Circumscribed flat area of colour change 1 cm or less in diameter
Patch >1cm
Define papule
Discrete elevation 1 cm or less
Define nodule
Like papule but deeper into dermis/ subcutaneous layer, > 1cm
Define plaque
Raised area > 1 cm diameter with flat top
Define petechia / purpura
Petechia = tiny macules due to extravascular blood in dermis
purpura = larger, may be palpable
Name 5 features malignant melanoma
ABCDE
- asymmetry
- border irregular
- colour irregular
- Diameter > 0,5 cm
- elevation irregular
Loss of skin markings
Name 8 causes scaly rashes
- Atopic eczema: face+flexures, shiny nails, “dirty neck “, infra-orbital crease
- psoriasis: extensor surfaces + lower back , nail pitting/ onycholysis, kobner phenomenon
- pityriasis rosea: ‘ fir tree” pattern on trunk, herald patch, well defined
- drug eruption
- pityriasis versicolor: upper trunk + shoulders
- lichen planus: distal limbs + flexural aspect wrists + lower back, white lacy network on buccal mucosa
- tinea corporis: asymmetrical isolated lesions
- secondary syphilis: trunk + proximal limbs + palms+ soles, history chancre
Name 5 causes vesicular rash
Localised:
- HSV
- HZV
- impetigo
- pompholyx / dyshidrotic eczema
Generalised:
- Eczema herpeticum (mucosal involvement)
- dermatitis herpetiformis
- acute eczema
Name 5 causes bullOus rash
Localised
- impetigo
- cellulitis
- stasis oedema
- acute eczema
- insect bite
- fixed drug eruption
Generalised
- ten (mucosal involvement)
- erythema multiforme
- Steven’s Johnson syndrome (mucosal involvement)
- lupus erythematosus
- porphyria cutanea tarda
- bullous pemphigoid
- pemphigus (mucosal involvement)
- epidermolysis bullOsa acquisita
- pseudo porphyria
Main differential for toxic epidermal necrolysis?
Staphylococcal scalded skin syndrome
Describe the Disease severity score for toxic epidermal necrolysis (SCORTEN) (7)
- Age > 40
- HR > 120
- cancer / haematological malignancy
- involved body surface area > 10%
- blood urea > 10 mmo/ l
- serum bicarb < 20 mmol/l
- glucose 14 or more mmol/l
Mortality rate:
0-1 factors = 3%
2=12%
3=35%
4=58%
5 or more: 90%
Name 2 other organs involved in ten
Ocular and urethral scarring
